/Engine/Plugins/Runtime/MeshModelingToolset/Source/ModelingComponents/Public/Mechanics/DragAlignmentMechanic.h
This will draw a line from the last input position to the last output position. This gets cleared when the transform is ended.
virtual void RenderInternal ( [IToolsContextRenderAPI](API\Runtime\InteractiveToolsFramework\IToolsContextRenderAPI) * RenderAPI )